diff --git a/algorithms/neat/population.py b/algorithms/neat/population.py
index 90ccbac..0119a28 100644
--- a/algorithms/neat/population.py
+++ b/algorithms/neat/population.py
@@ -64,7 +64,7 @@ def update_species(randkey, fitness, species_info, idx2species, center_nodes, ce
 
     # decide the number of members of each species by their fitness
     spawn_number = cal_spawn_numbers(species_info, jit_config)
-
+    # jax.debug.print("spawn_number: {}", spawn_number)
     # crossover info
     winner, loser, elite_mask = \
         create_crossover_pair(randkey, species_info, idx2species, spawn_number, fitness, jit_config)
@@ -135,13 +135,16 @@ def cal_spawn_numbers(species_info, jit_config):
     spawn_number_rate = jnp.where(is_species_valid, spawn_number_rate, 0)  # set invalid species to 0
 
     target_spawn_number = jnp.floor(spawn_number_rate * jit_config['pop_size'])  # calculate member
+    # jax.debug.print("denominator: {}, spawn_number_rate: {}, target_spawn_number: {}", denominator, spawn_number_rate, target_spawn_number)
 
     # Avoid too much variation of numbers in a species
     previous_size = species_info[:, 3].astype(jnp.int32)
     spawn_number = previous_size + (target_spawn_number - previous_size) * jit_config['spawn_number_move_rate']
-
+    # jax.debug.print("previous_size: {}, spawn_number: {}", previous_size, spawn_number)
     spawn_number = spawn_number.astype(jnp.int32)
 
+    # spawn_number = target_spawn_number.astype(jnp.int32)
+
     # must control the sum of spawn_number to be equal to pop_size
     error = jit_config['pop_size'] - jnp.sum(spawn_number)
     spawn_number = spawn_number.at[0].add(error)  # add error to the first species to control the sum of spawn_number
@@ -254,7 +257,8 @@ def speciate(pop_nodes, pop_cons, species_info, center_nodes, center_cons, gener
         distances = o2p_distance_func(cn[i], cc[i], pop_nodes, pop_cons, jit_config)
 
         # find the closest one
-        closest_idx = argmin_with_mask(distances, mask=jnp.isnan(idx2specie))
+        closest_idx = argmin_with_mask(distances, mask=jnp.isnan(i2s))
+        # jax.debug.print("closest_idx: {}", closest_idx)
 
         i2s = i2s.at[closest_idx].set(species_info[i, 0])
         cn = cn.at[i].set(pop_nodes[closest_idx])
@@ -268,13 +272,17 @@ def speciate(pop_nodes, pop_cons, species_info, center_nodes, center_cons, gener
     _, idx2specie, center_nodes, center_cons, o2c_distances = \
         jax.lax.while_loop(cond_func, body_func, (0, idx2specie, center_nodes, center_cons, o2c_distances))
 
+    # jax.debug.print("species_info: \n{}", species_info)
+    # jax.debug.print("idx2specie: \n{}", idx2specie)
+
     # part 2: assign members to each species
     def cond_func(carry):
         i, i2s, cn, cc, si, o2c, ck = carry  # si is short for species_info, ck is short for current key
-        jax.debug.print("{}, {}", i, i2s)
+        # jax.debug.print("i:\n{}\ni2s:\n{}\nsi:\n{}", i, i2s, si)
+        current_species_existed = ~jnp.isnan(si[i, 0])
         not_all_assigned = jnp.any(jnp.isnan(i2s))
         not_reach_species_upper_bounds = i < species_size
-        return not_all_assigned & not_reach_species_upper_bounds
+        return current_species_existed | (not_all_assigned & not_reach_species_upper_bounds)
 
     def body_func(carry):
         i, i2s, cn, cc, si, o2c, ck = carry  # scn is short for spe_center_nodes, scc is short for spe_center_cons
@@ -324,8 +332,8 @@ def speciate(pop_nodes, pop_cons, species_info, center_nodes, center_cons, gener
         close_enough_mask = o2p_distance < jit_config['compatibility_threshold']
 
         # when a genome is not assigned or the distance between its current center is bigger than this center
-        cacheable_mask = jnp.isnan(i2s) | (o2c > o2p_distance)
-
+        cacheable_mask = jnp.isnan(i2s) | (o2p_distance < o2c)
+        # jax.debug.print("{}", o2p_distance)
         mask = close_enough_mask & cacheable_mask
 
         # update species info
diff --git a/configs/default_config.ini b/configs/default_config.ini
index 67bdb92..3533f65 100644
--- a/configs/default_config.ini
+++ b/configs/default_config.ini
@@ -13,16 +13,16 @@ batch_size = 4
 fitness_threshold = 100000
 generation_limit = 1000
 fitness_criterion = "max"
-pop_size = 100
+pop_size = 50
 
 [genome]
 compatibility_disjoint = 1.0
 compatibility_weight = 0.5
-conn_add_prob = 0.5
+conn_add_prob = 0.4
 conn_add_trials = 1
-conn_delete_prob = 0
+conn_delete_prob = 0.4
 node_add_prob = 0.2
-node_delete_prob = 0
+node_delete_prob = 0.2
 
 [species]
 compatibility_threshold = 3.0